PROJECT SUMMARY Here, we seek funding to purchase a modern, intermediate voltage (300 kV) transmission electron microscope (F30 Polara). This microscope will replace the existing FEI Tecnai F20 at Sanford-Burnham Medical Research Institute (SBMRI). The F30 will be integrated into an existing unit that comprises of cryo-TEMs and ancillary equipment. It will provide the means for a more robust, high-quality/high-throughput cryo-tomography data acquisition at LN2 temperatures by semi-automation of sample handling and more robust screening capabilities, better and more powerful electron optics, LN2 stable stage and higher rates of tilt series completion. Together, this upgrade will allow us to optimize data quality and resolution for a broad range of biological samples from our scientific teams, enabling us to correlate molecular mechanisms and functional outputs, to provide scale-integrated models of disease, and to provide new perspectives for the development of new therapeutics. The proposed instrumentation upgrade will support teams of scientists from SBMRI and researchers from TSRI, UCSD, UCLA, Yale University, University of Virginia School of Medicine, Harvard Medical School, Stowers Institute for Medical Research, and the University of New Mexico Health Sciences Center. All these researchers are funded through project grants from the NIH to pursue a broad range of health-related studies in the areas of developmental biology, inflammation, innate immunity, bone mineralization, metastasis, and infectious diseases. All of the projects highlighted in this application employ cryo-tomography imaging, ranging from tomography of single macromolecular assembly structure determination to in-situ whole cell tomography. These projects are only representatives of a potentially much larger pool of projects that could greatly benefit from access to this dedicated, modern cryo-tomography F30 scope.